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Structural mechanics & thermal conduction: How to put an stressfree layer on a stressed assembly?

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Hi

I want to put a layer with zero stress on a stressed assembly. This is something that occurs often in manufacturing.

Let's assume a mechanical assembly with some internal stress causing mechanical deformation of the assembly (e.g. caused by different thermal expansion of the assembly materials)? How can you SUBSEQUENTLY put a stressfree layer on top of the stressed assembly?

Many thanks


2 Replies Last Post 28 set 2010, 07:46 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 27 set 2010, 07:17 GMT-4
Hi
I see two ways, but it depends im my view of how the stress is present wehn "assembling" the parts so that the model represents truely the "real case"

One is to set the initial stress values for one of the two domains, but this means to set the true stress tensor values, this is not trivial, but could be obtained from a stationary analysis, and then partly changed/adapted manually.

The second is to change a parameter per domain, i.e. two plates with each a different temperature T (full thermal isolation between them, no conduction steady state T). I would say this is the "old" engineering way, as the structural strengths of both material participate then to have a contium at the interface. On can also set different temperature profiles on the different materials.

If you issue is a true temperature stress induced case, then you use normal thermal conduction and contact resistance, but you play with the time variation of the temperature, I believe there is soemwhere an example of a thermal stress fit axis

hope this helps

--
Good luck
Ivar
Hi I see two ways, but it depends im my view of how the stress is present wehn "assembling" the parts so that the model represents truely the "real case" One is to set the initial stress values for one of the two domains, but this means to set the true stress tensor values, this is not trivial, but could be obtained from a stationary analysis, and then partly changed/adapted manually. The second is to change a parameter per domain, i.e. two plates with each a different temperature T (full thermal isolation between them, no conduction steady state T). I would say this is the "old" engineering way, as the structural strengths of both material participate then to have a contium at the interface. On can also set different temperature profiles on the different materials. If you issue is a true temperature stress induced case, then you use normal thermal conduction and contact resistance, but you play with the time variation of the temperature, I believe there is soemwhere an example of a thermal stress fit axis hope this helps -- Good luck Ivar

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 28 set 2010, 07:46 GMT-4
Hi
have you checked the layered_plate thermal library model, does this look like your case ?

--
Good luck
Ivar
Hi have you checked the layered_plate thermal library model, does this look like your case ? -- Good luck Ivar

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